This invention relates to spiral tube making methods and apparatus, and more particularly to rejecting finished tube sections which include splices in any one of the constituent strips or tapes.
Machinery for making spiral wound tubes from one or more input strips or tapes of paper, plastic, metal foil, or the like are well known as shown, for example, by Meyer U.S. Pat. No. 4,473,368. The strips are typically supplied from large rolls or reels, and in order to keep the machine running continuously or substantially continuously, it is desirable to splice the trailing end of each supply roll which is about to be exhausted to the leading end of a new roll. The problem with doing this is that the splice becomes part of one or possibly two or more adjacent lengths of finished tube. Although splices may be difficult to automatically detect in the finished tube, they frequently render the affected tube lengths unacceptable or at least undesirable for their intended use (e.g., by locally increasing their thickness, outer circumference, weight, etc.). A way to identify and reject tube lengths containing splices is therefore needed.
In view of the foregoing, it is an object of this invention to improve spiral tube winding methods and apparatus.
It is a more particular object of this invention to provide spiral tube winding methods and apparatus which can detect a splice in any of the strips or tapes going to the winding mechanism and reject the length (or lengths) of finished tube containing such a splice.